I have an international HTC One with ViperOne 5.5.1.
I recently made my phone S-OFF (it has 1.54).

Now the problem: As soon as I try to flash either a kernel or a bootscreen, the phone reboots. I currently have CWM Touch (just 5 minutes now, I flashed CWMT because TWRP had the same problem). The problem is not in the recovery, since they both don't work. Fastboot works (I could flash a different recovery). It's just that as soon as something tries to flash into /system, the phone reboots itself. I tried pushing the bootscreen via adb, but that gave a 'protocol failure.'

tl;dr: Phone reboots while flashing in both TWRP and CWM Touch, eventually it didn't flash anything at all.

I have an international HTC One with ViperOne 5.5.1.
I recently made my phone S-OFF (it has 1.54).

Now the problem: As soon as I try to flash either a kernel or a bootscreen, the phone reboots. I currently have CWM Touch (just 5 minutes now, I flashed CWMT because TWRP had the same problem). The problem is not in the recovery, since they both don't work. Fastboot works (I could flash a different recovery). It's just that as soon as something tries to flash into /system, the phone reboots itself. I tried pushing the bootscreen via adb, but that gave a 'protocol failure.'

tl;dr: Phone reboots while flashing in both TWRP and CWM Touch, eventually it didn't flash anything at all.

I am beyond reasoning and have no clue on what to do.

Try this: go back to recovery (TWRP 2.6.3.3. or .4 recommended for 4.4 ROMs at the moment)

dirty-flash the ROM, then while still in recovery (no reboot), flash kernel, etc.
then reboot

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